In English, there is some difference between don’t have to, don’t need to, needn’t, shouldn’t. For Hungarian people it is just nem kell or nem kellene. The rest can be understood from the context.

OTHER USES FOR KELL AND KELLENE

You can use kell/kellene not only as modal verbs, but also as main verbs. In this case, they can be translated as:

to need

and it requires -nak, -nek to express a person/thing needs something.

Nem kellenének a füzetek? – Don’t you need the notebooks?Kellettek ezek a tollak? – Did you need this pen?Kellenének az iratok, de azonnal! – I need the documents right now!
Ha gazdag lennél, se kellennél nekem. – Even if you were rich, I wouldn’t want you.Kinekkell ez a sok pénz? – Who wants that much money?Mindenkinek kell egy kis sikerélmény. – Everyone needs a little success.

NOTE! The future tense for kell as modal verb is: kell majd. You can’t say kelleni fog in that case. However, as a main verb, it can have the future tense with fog or with majd: kelleni fog, kell majd. You choose.